This invention is an improvement over U.S. Pat. No. 4,304,244, issued Dec. 8, 1981; U.S. Pat. No. 4,324,263, issued April 13, 1982; and U.S. Pat. No. 4,373,540, issued Feb. 15, 1983 which disclose compositions and methods for treating hair wherein the compositions contain, as a principal active ingredient, guanidine hydroxide. The guanidine hydroxide is prepared by reacting a water-soluble inorganic hydroxide, such as calcium hydroxide, with a water-soluble guanidine salt, such as guanidine carbonate. The guanidine hydroxide composition is applied to the hair for a selected period of time to, for example, relax or straighten the hair. Thereafter, the hair may be rinsed and neutralized.
Guanidine hydroxide is rapidly converted, when in the presence of carbon dioxide, into guanidine carbonate, which is inactive as a hair treating agent. Furthermore, in the presence of moisture, the guanidine hydroxide decomposes into lower molecular weight compounds which are also inactive as hair treating agents. Thus, the guanidine hydroxide compositions are presently marketed in a two component system, with the guanidine carbonate being in one container, and the calcium hydroxide being in a separate container, the two container contents being mixed just prior to the hair treatment.